The invention relates to air intake silencer boxes for marine engines. An air box is typically mounted to the air intake throat of the carburetor for directing air thereto and for silencing engine noise emitted back through the carburetor throat.
An air box is an air chamber with tubes of predetermined length and area connecting the inside of the box to the outside environment. Prior boxes have typically been a multipiece assembly, including a die cast metal plate with tubes cast in place and mounted to the carburetor. An air box cover and gasket are mounted to the plate and held in place by screws threaded into tapped openings in the plate. Two cycle engines have a tendency to spit fuel back out through the carburetor throat, which fuel collects in the bottom of the air box. A fitting may be included in the bottom of the box to drain such fuel. Fuel leakage from the box has been a continuing problem, particularly at the noted gasket.
The present invention provides a solution to the above noted and other problems. In preferred form, a two piece injection molded thermoplastic air box has air guide passages and an air plenum chamber all molded in place. The two housing sections are preassembled to each other and sealed along a peripheral seam. The assembly does not leak, reduces weight, reduces assembly time, and substantially reduces cost.
After the box is preassembled and sealed, it is mounted to the air intake throat of the carburetor or other fuel delivery structure such as a fuel injection manifold. A base section of the assembly has an aperture therethrough over the throat, and means are provided for mounting the base section to the throat. A cover section of the assembly has a removable plug which upon removal allows access to the base section and mounting means through the cover section to permit mounting of the base section to the throat by the mounting means, followed by replacement of the plug.
In a particularly desirable aspect of the invention in combination with a carburetor having a fuel adjustment screw adjacent the air intake throat, the assembly includes structure enabling the adjusting screw to be adjusted with the air box mounted in place on the carburetor throat, to faciliate more accurate adjustment of the carburetor by enabling adjustment under actual operating conditions, with the entire assembled air box in place.